1664664671 has 2 divisors, whose sum is σ = 1664664672. Its totient is φ = 1664664670.

The previous prime is 1664664643. The next prime is 1664664707. The reversal of 1664664671 is 1764664661.

It is a happy number.

It is a weak prime.

It is an emirp because it is prime and its reverse (1764664661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1664664671 - 2⁶ = 1664664607 is a prime.

It is a super-2 number, since 2×1664664671² = 5542216933751076482, which contains 22 as substring.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1664664571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832332335 + 832332336.

It is an arithmetic number, because the mean of its divisors is an integer number (832332336).

Almost surely, 2^1664664671 is an apocalyptic number.

1664664671 is a deficient number, since it is larger than the sum of its proper divisors (1).

1664664671 is an equidigital number, since it uses as much as digits as its factorization.

1664664671 is an evil number, because the sum of its binary digits is even.

The product of its digits is 870912, while the sum is 47.

The square root of 1664664671 is about 40800.3023395661. The cubic root of 1664664671 is about 1185.1561856245.

The spelling of 1664664671 in words is "one billion, six hundred sixty-four million, six hundred sixty-four thousand, six hundred seventy-one".